A mesoporous graphene @ zirconium-based metal-organic frameworks as a matrix and an adsorbent for steroid detection using surface-assisted laser desorption/ionization time-of-flight mass spectrometry.

Endocrine-disrupting chemicals (EDCs) in environmental water samples, a rapid, sensitive, and high-throughput method should be developed. In this study, an in situ-synthesized composite material of three-dimensional mesoporous graphene (3D-MG) and zirconium-based metal-organic frameworks (MOFs), denoted as MG@UiO-66, was used as both the adsorbent and matrix in surface-assisted laser desorption/ionization time-of-flight mass spectrometry (SALDI-TOF MS) for steroid detection. Both graphene-based materials and MOFs have proven to be ineffective in detecting steroids as a matrix; however, their composites can detect steroids with higher sensitivity and lower interference. After screening different types of MOFs, a composite of UiO-66 and 3D-MG was selected as the new matrix for steroid detection. The combination of 3D-MG and UiO-66 further enhanced the ability of the material to enrich steroids, and reduced the limit of detection (LOD) of steroids. The method was evaluated for linearity, LODs, limit of quantitation (LOQs), reproducibility, and precision under optimized conditions. The results showed that the linear relationships of three steroids are kept in the range of 0-300 nM/L with a correlation coefficient r ≥ 0.97. The LODs and LOQs of the steroids were in the range of 3-15 and 10-20 nM/L, respectively. Recoveries (n = 5) of 79.3-97.2% were obtained at three spiked levels in the blank water samples. This fast and efficient method of using SALDI-TOF MS can be extended to detect the steroids in EDCs in environmental water samples.

Molecularly imprinted polymers based on magnetic metal-organic frameworks for surface-assisted laser desorption/ionization time-of-flight mass spectrometry analysis and simultaneous luteolin enrichment.

UiO-66(NH2), a metal-organic framework, exhibits excellent UV absorption and energy transfer performance and can be used as a substrate for surface-assisted laser desorption/ionization (SALDI) analysis of small molecules. Molecularly imprinted polymers (MIPs) exhibit outstanding selectivity toward certain targets. The complexes of UiO-66(NH2) and MIPs can be applied as both an adsorbent and substrate for SALDI-time-of-flight mass spectrometry (SALDI-TOF MS) analysis of small molecules. Herein, magnetic UiO-66(NH2)-molecularly imprinted polymers (MUMIPs) were prepared for the selective enrichment and detection of luteolin via SALDI-TOF MS. The amino group on UiO-66(NH2) were used as functional monomer to prepare MIPs that interact with luteolin via hydrogen bonding. The surface functional monomer can effectively control the coating thickness of the MIPs to avoid embedding template molecules and enhance adsorption performance. In addition, Fe3O4 particles were introduced for rapid magnetic separation. The physicochemical properties of the MUMIPs were characterized via scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermal gravimetric analysis, vibrating sample magnetometry, Brunauer-Emmett-Teller analysis, and X-ray photoelectron spectroscopy. Adsorption experiments and selectivity studies indicated that MUMIPs exhibited good adsorption capacity, fast adsorption rates, and excellent luteolin selectivity. MUMIPs are efficient substrates for the SALDI analysis of luteolin and its structural analogs. In addition, the MUMIPs-SALDI-TOF MS method successfully detected luteolin in rat plasma and urine after administration of oral Chrysanthemum morifolium Ramat extracts. This method possessed high sensitivity with a limit of detection of 0.5 ng/mL. The traditional precipitation method combined with high-performance liquid chromatography-mass spectrometry was also used to analyze luteolin in biological samples. Compared with the traditional method, the novel MUMIP-SALDI-TOF MS method can more effectively detect the target compounds in complex samples. Ultimately, the MUMIP-SALDI-TOF MS method was applied to detect luteolin and its metabolites in rat liver after oral luteolin treatment. Three luteolin metabolites (apigenin, chrysoeriol, and diosmetin) were analyzed using the newly developed MUMIP-SALDI-TOF MS method.

Microwave-prepared mesoporous graphene as adsorbent and matrix of surface-assisted laser desorption/ionization mass spectrometry for the enrichment and rapid detection of polyphenols in biological samples.

In this work, a three-dimensional mesoporous graphene (3D-MG) prepared by microwave-assisted method was used as both the adsorbent and the matrix of SALDI-TOF MS for polyphenols analysis in biological samples. The outstanding microstructure of 3D-MG made it sensitive in small molecule analysis with low background interference and able to enrich trace polyphenols from complex samples. 3D-MG performed much better in the detection of small molecules than graphene prepared by ordinary method, and could further improve sensitivity and reduce detection limit by enrichment. Due to its unique hierarchical mesoporous structure, the interference of biological macromolecules in SALDI analysis could be eliminated after treatment by 3D-MG. Finally, 3D-MG was successfully applied to the screening of polyphenols in biological samples with simple process and high throughput. Moreover, this strategy had also promoted the development of new matrix in SALDI-TOF MS analysis, in which the matrix properties, adsorption capabilities and size effects of graphene-based materials were combined for the first time.

Rapid synthesis of three-dimensional sulfur-doped porous graphene via solid-state microwave irradiation for protein removal in plasma sample pretreatment.

In this work, we prepared three-dimensional sulfur-doped porous graphene (3D-SPG) via solid-state microwave method and first introduced it to plasma sample pretreatment as adsorbent for the removal of proteins. The efficient heating effect of solid-state microwave irradiation endowed the as-prepared 3D-SPG with large specific surface area, porous structures and sulfur-doped conjugated π electron surface, thus producing an outstanding adsorbent for proteins adsorption. The adsorption behavior of 3D-SPG towards proteins was explored using bovine serum albumin (BSA) as the model protein and several kinetic models and isotherm models were employed to describe the adsorption process. The results indicated that BSA was adsorbed onto 3D-SPG in a monolayer manner with high adsorption capacity, and chemisorption and intraparticle diffusion was the rate-controlling step in proteins adsorption process. By applying 3D-SPG as adsorbent to remove proteins in real rat plasma, we found that 3D-SPG solid phase extraction (SPE) gained exceedingly high protein removal efficiency compared with other plasma pretreatment methods, suggesting that 3D-SPG SPE could effectively prevent the deterioration of column performance and decrease the interference caused by matrix effect in the follow-up analysis. Furthermore, in comparison with the tandem mass spectra results between 3D-SPG SPE and methanol precipitation, 3D-SPG SPE demonstrated the ability to extract the protein-binding metabolites which usually could not be extracted by methanol precipitation. This ability made 3D-SPG SPE of great value in untargeted metabolomics profiling, because 3D-SPG SPE could be a complementary method to methanol precipitation to improve the coverage of metabolites.

Water environmental stress, rebound effect, and economic growth of China's textile industry.

The rapid development of China's textile industry (TI) has led to severe water environmental stress. Water environmental stress of China's TI mainly comes from large quantities of discharged wastewater and chemical oxygen demand (COD). The sustainable development of the TI is realized to achieve the decoupling between economic growth and water environmental stress. This study analyzes the decoupling elasticity results from wastewater discharge and COD discharge, respectively. Decoupling results show that TI's wastewater has strong decoupling from economic growth for three years (2002, 2013-2014) while COD has strong decoupling for six years (2002-2003, 2008, 2010, 2013-2014). The paper further calculates the decoupling elasticity results of the TI's three sub-sectors (manufacture of textile sector, manufacture of textile wearing and apparel sector, and manufacture of chemical fibers (MCF) sector), and calculates the factors that affect wastewater discharge. The decrement and rebound effects of wastewater discharge are analyzed based on calculated results. Decomposition results show that the scale factor is the most significant contributor to wastewater discharge, the intensity factor inhibits wastewater discharge, and the effect of the structure factor is not evident. The decrement effect of TI increases yearly, but the rebound effect shows that the absolute amount of wastewater discharge also increases. The rebound effect has declined since 2012. In the three sub-sectors, MCF's decrement effect is the strongest, and its rebound effect is the weakest, which indicate that MCF is the biggest contributor to the discharge reduction of China's TI.